The current minimum version of LibreOffice is version 5.0.5, but the version here is 3.3.0. There are a bunch of security patches between the two, and, unfortunately, unlike Firefox and Thunderbird, LibreOffice can’t update itself. You have to re-download the whole thing. But how do I take the contents of the current version and put them into the portable version to update it?

And, as a related question, can we apply the LibreOffice language packs to the portable version, or do we need to create a language version and then make it portable?

Just Ctrl+click on your PortableOffice.app icon and select Show package content and copy your new localized version there in place of old one.
Not tested so not sure it works with new version. Do backup.